Kiln cars are well known in the industry and have been described in prior publications and patents. These cars typically are used to transport ceramic and/or other refractory material (e.g., bricks, vases, porcelain fixtures, etc.) through heated ovens (i.e., "kilns") for the purpose of curing/firing the material at elevated temperatures.
The chassis of a conventional kiln car is normally made of heavy gage steel. A heat-barrier layer is positioned above the chassis of the kiln car.
The material being fired/cured generally rests on a deck which is typically composed of a plurality of ceramic or refractory-type tiles. The deck, in turn, is supported above the kiln car chassis by a plurality of vertically oriented support posts which pass upwardly from the kiln car chassis through the heat-barrier layer. Sometimes, there are supporting beams positioned between the support posts and the deck plates.
In some instances, the deck plates or support beams rest directly on the upper ends of the posts. However, for better support, it is desirable to have a larger surface area upon which the deck and/or beam can rest. Since it is also desirable to minimize the size and number of physical obstructions between the deck and the heat barrier layer, the support posts are sometimes molded such that their upper ends have a larger surface area than that which would be provided by the diameter of the posts' vertical section. Examples of such types of post designs are illustrated in U.S. Pat. Nos. 4,110,069 and 4,897,034.
Regardless of the type of post design employed, there is one typical and recurring problem inherent thereto. Specifically, the upper portion of the support post, which supports the deck, support beam and/or material being fired, frequently breaks and/or cracks due to the physical and thermal shocks inherent in typical kiln-firing processes.
When the upper supporting end of a support post breaks, the entire post must be replaced. As would be expected, this is a costly and time-consuming process.
To overcome the problem associated with replacing an entire post, many users of kiln cars employ what are commonly known in the industry as "post caps". Post caps are generally manufactured of ceramic or refractory-type materials. The upper surface of a post cap typically has a surface area which is larger than the cross-sectional area of the upper end of a support post.
As indicated by its name, a post cap is generally made to rest on the upper end of a support post. Examples of different types and designs of post caps typically employed in the kiln-firing industry are illustrated in U.S. Pat. Nos. 4,773,805; 4,721,459; 4,348,175; 4,330,276 and 1,665,631.
As with a single molded post having its upper supporting surface enlarged (e.g., those illustrated in U.S. Pat. Nos. 4,897,034 and 4,110,069), post caps also frequently break and/or crack due to the physical and thermal shocks encountered in typical kiln-firing processes. Therefore, while the use of post caps does rectify some of the problems associated with replacing the entire post, the mere use of conventional post caps does not, itself, decrease the frequency of cracks and/or breaks occurring during typical kiln-firing processes.
To the inexperienced lay person, it may seem obvious to mold thicker post caps to provide the desired additional strength. To those skilled in the art, however, this is undesirable since a thicker post cap will absorb a larger portion of the kiln heat, thus requiring the use of more energy to achieve the necessary firing conditions.
Therefore, if not for the loss in strength, a skilled artisan would be led to use smaller/thinner post caps. However, as would be expected, smaller/thinner post caps have a greater tendency of cracking and/or breaking when subjected to the physical and thermal shocks encountered in typical kiln-firing processes. Consequently, the kiln-firing industry has been plagued with a dilemma, since employing a means of satisfying one of the desirable properties for post caps (e.g., using a thicker/larger post cap for added strength) detracts from one of the other highly desirable properties (e.g., minimizing the amount of energy needed to achieve the desired kiln firing conditions).
Although it would have been a welcomed improvement in the kiln-firing industry, prior to the present invention, no one has been able to design and/or fabricate a post cap which can withstand much of the physical and thermal shocks encountered by kiln cars, while not absorbing a substantial amount of additional heat.
Another major problem often encountered in the kiln-firing industry is the shifting and/or buckling of the deck while the kiln car is in use. As stated earlier, kiln cars customarily have decks made from a number of plates which have flat upper and lower surfaces. These plates are generally designed to lay flat on the upper surface of the support posts, post caps or support beams. Since kiln cars are subject to physical and thermal shocks when in use, the deck plates and/or support beams often buckle and shift. This can be catastrophic in the kiln-firing industry since it can result in the deck collapsing while the car is within the kiln. Therefore, it is also extremely desirable to have a means for minimizing the amount of shifting and/or buckling of deck plates when subjected to the normal physical and thermal shocks encountered in typical kiln-firing processes.
As expected, breaks and/or cracks are not limited to post caps. Often, regardless of whether a post cap is employed, the support post itself cracks and/or breaks. When this occurs, the typical response in the kiln-firing industry is to replace the entire post. Obviously, the larger the post the greater its replacement costs (i.e., the cost of replacing a two foot post is less than that of replacing a four foot post). In view of the above, it would also be a welcomed improvement in the kiln-firing industry if a method can be devised for eliminating the need to replace the entire post and/or minimizing the cost of repairing the same.